the fundamental source code for the app you need is freely available in Apple’s developer support webpages … its called Movie Assembler
MovieAssembler
Requires: Mac OS X 10.4. Final Cut Pro 5.1.2 or later. Xcode 2.1 or later.
The MovieAssembler sample application demonstrates the use of several new
capabilities in Final Cut Pro 5.1.2:
– AppleEvent commands to communicate with and control Final Cut Pro.
– QuickTime metadata to identify and process movie files.
– Version 3 of the Final Cut Pro XML Interchange Format to access and
modify the contents of sequences in Final Cut Pro project files.
Once configured properly, MovieAssembler monitors a watch folder for
newly copied media files. It uses ID tag(s) stored as metadata to specify
if and where a particular media file should be inserted into a selected
sequence.
you may need to download and install the latest Developer tools to build the application, and of course you will have to write any additional code needed to adapt this to your particular workflow